The present invention relates to an apparatus for attaching an elastic member to a disposable diaper and, more particularly, to an apparatus adapted to cut the elastic member for fitness of opposite side edges around the user's legs into desired lengths and then to successively attach these lengths of the elastic member onto a continuous diaper web.
In the conventional disposable diaper of so-called drawers type, the elastic member of rubber are attached to the opposite side edges of the diaper to achieve a good fitness of these side edges around the user's legs as already disclosed in U.S. Pat. No. 3,860,003. As the means for attaching such elastic member, so-called snapback method is well known and disclosed, for example, in U.S. Pat. No. 4,081,301. According to this snapback method, adhesive is applied onto a continuous elastic member longitudinally at regular intervals, this continuous elastic member is affixed with interposition of layer of thus applied adhesive onto inner surface(s) of a substantially non-elastic continuous diaper web, i.e., a backsheet and/or a topsheet, then the continuous diaper web is severed at adhesive-free portions of said elastic member into individual diapers and simultaneously said adhesive-free portions in the individual diapers are retracted from the severed ends of the respective diapers under a contractibility of these adhesive-free portions.
When this snapback method is adopted, the severed ends of the individual diaper must be provided with portions left open, through which the severed ends of the adhesive-free elastic member portions can be retracted into the individual diaper under the contractibility of the elastic member itself. Thus, the conventional disposable diaper manufactured according to this snapback method has often been susceptible to leakage of urea through such open portions of the side edges.
Also when this snapback method is adopted, the elastic member is maintained stretched and attached by adhesive applied thereon longitudinally at regular intervals onto the continuous diaper web which is also maintained under a predetermined tension during moved through steps of manufacturing. During this movement, the elastic member may sometimes partially deviate transversely of the continuous diaper web under an external force before the adhesive has not been adequately hardened. In such a case, the above-mentioned partial deviation may affect the rest of the elastic member since the latter is continuous. This may prevent the adhesive from properly functioning and, after the continuous diaper web has been severed into the individual diapers, the portions of the elastic member which should be affixed onto the diaper web may be peeled off therefrom during handling and use of the individual diapers.
A principal object of the present invention is to provide an apparatus for attaching an elastic member in a disposable diaper adapted to overcome the drawbacks encountered by the apparatus or the method of prior art.
Other objects will be apparent from the following description of preferred embodiments of the present invention.